Binder resin for toners

Abstract

A binder resin for high image quality toners used in copying machines and printers by electrophotography which are excellent in anti-offset property, fixing property, blocking resistance, and image characteristics obtained by controlling the molecular weight, blend ratio, acid value, and ratio of a high molecular weight polymer and a low molecular weight polymer of the binder resin to specific values.

We claim: 
     
       1. A binder resin blend for toners comprising a styrene-vinyl copolymer blend having an acid value (AV T ) of not greater than 20 mg KOH/g and an AV H  /AV L  ratio of 0.025 to 40, containing up to no more than 1,000 ppm of residual monomers and/or a residual solvent, and having a glass transition temperature of 50° to 68° C. and a softening temperature of 110° to 145° C., wherein the vinyl monomer component of the copolymers of the blend is selected from the group consisting of (meth)acrylic acid, (meth)acrylic acid esters, maleic acid and esters thereof, fumaric acid and esters thereof, addition monomers of ε-caprolactam with acrylic monomers and bisphenol A adducts of acrylic monomers, the copolymers of the blend being comprised of 15 to 40% by weight of a high molecular weight polymer having a weight average molecular weight of 3×10 5  to 1.5×10 6  and an acid value (AV H ) of 0.5 to 20 mg KOH/g and 60 to 85% by weight of a low molecular weight polymer having a weight average molecular weight of 3×10 3  to 6×10 4  and an acid value (AV L ) of 0.5 to 20 mg KOH/g.   
     
     
       2. The binder resin blend for toners according to claim 1 wherein the high molecular weight polymer has a weight average molecular weight of 4×10 5  to 9×10 5 . 
     
     
       3. The binder resin blend for toners according to claim 1 wherein the low molecular weight polymer has a weight average molecular weight of 4×10 3  to 5×10 4 . 
     
     
       4. The binder resin blend for toners according to claim 1 wherein the content of the high molecular weight polymer is 20 to 35% by weight. 
     
     
       5. The binder resin blend for toners according to claim 1 wherein the content of the low molecular weight polymer is 65 to 80% by weight. 
     
     
       6. The binder resin blend for toners according to claim 1 wherein the high molecular weight polymer has an acid value (AV H ) of 0.5 to 15 mg KOH/g. 
     
     
       7. The binder resin blend for toners according to claim 1 wherein the low molecular weight polymer has an acid value (AV L ) of 0.5 to 15 mg KOH/g. 
     
     
       8. The binder resin blend for toners according to claim 1 wherein the AV H  /AV L  is 0.025 to 30. 
     
     
       9. The binder resin blend for toners according to claim 1 wherein the acid value (AV T ) is not not greater than 15 mg KOH/g. 
     
     
       10. The binder resin blend for toners according to claim 1 wherein the amount of the residual monomers and/or a residual solvent is less than 800 ppm. 
     
     
       11. The binder resin blend for toners according to claim 1 wherein the glass transition temperature is 54° to 66° C. 
     
     
       12. The binder resin blend for toners according to claim 1 wherein the softening temperature is 120° to 140° C. 
     
     
       13. A The binder resin blend for toners according to claim 1 wherein the molecular weight (M W   H ) of the greatest peak in a high molecular weight region and the molecular weight (M W   L ) of the greatest peak in a low molecular weight region are in the relationship represented by the following equation (1): 
     
     
       14. A binder resin blend for toners comprising a styrene copolymer prepared from a styrenic monomer and a vinyl monomer, or a blend of styrene-vinyl copolymers, wherein the vinyl monomer of the copolymer or the copolymer of the blend is a member selected from the group consisting of (meth)acrylic monomers, (meth)acrylic monomer esters, maleic acid and esters thereof, fumaric acid and esters thereof, addition monomers of ε-caprolactam with acrylic monomers and bisphenol A adducts of acrylic monomers, having at least one maximum value in the molecular weight region of 10 3  to 7×10 4 , at least one maximum value in the molecular weight region of 10 5  to 2×10 6 , and a shoulder in the molecular weight region greater than that of 5×10 5  in a molecular weight distribution having a maximum value of the greatest molecular weight, all in a chromatogram measured by gel permeation chromatography, wherein the molecular weight (M W   H ) of the greatest peak in the high molecular weight region and the molecular weight (M W   L ) of the greatest peak in the low molecular weight region have the relationship expressed by the equation (1):   1×10.sup.6 ≧M.sub.W.sup.H -M.sub.W.sup.L ≧2×10.sup.5                                  ( 1),     and     having a melt viscosity of 3×10 3  to 10 5  Pa.S at 120° C., a glass transition temperature of 50° to 68° C. and an acid value of 0.5 to 20 mg KOH/g.   
     
     
       15. The binder resin blend for toners according to claim 14 wherein the resin has a shoulder in the molecular weight region of 6×10 5  to 2×10 6 . 
     
     
       16. The binder resin blend for toners according to claim 14 wherein the resin has a shoulder in the molecular weight region of 6×10 5  to 10 6 . 
     
     
       17. The binder resin blend for toners according to claim 14 wherein the high molecular weight polymer having a maximum value in a region of a molecular weight of 105 to 2×10 6  is contained in the binder resin blend in an amount of 15 to 45% by weight. 
     
     
       18. The binder resin blend for toners according to claim 14 wherein the melt viscosity at 120° C. is 8×10 3  to 8×10 4  Pa.S. 
     
     
       19. The binder resin blend for toners according to claim 14 wherein the glass transition temperature is 54 to 66° C. 
     
     
       20. The binder resin blend for toners according to claim 14 wherein the softening temperature is 120° to 140° C. 
     
     
       21. A binder resin blend for toners comprising a styrene copolymer prepared from a styrenic monomer and a vinyl monomer, or a blend of styrenic-vinyl copolymers, wherein the vinyl monomer is a member selected from the group consisting of (meth)acrylic monomers, (meth)acrylic monomer esters, maleic acid and esters thereof, fumaric acid and esters thereof, addition monomers of ε-caprolactam with acrylic monomers and bisphenol A adducts of acrylic monomers, having at least one peak in the molecular weight region of 103 to 7×10 4  and the molecular weight region of 10 5  to 2×10 6  respectively, and having a shoulder in the molecular weight region less than that of a maximum value of the peak in the molecular weight region of 2×10 3  to 6×10 4 , all in the molecular weight distribution by gel permeation chromatography, and   having a glass transition temperature of 50° to 68° C., a softening temperature of 110° to 145° C., and an acid value of not greater than 40 mg KOH/g.   
     
     
       22. The binder resin blend for toners according to claim 21 wherein the resin has a peak in the molecular weight region of 2×10 3  to 6×10 4  and the region of molecular region of 3×10 5  to 2×10 6 , respectively. 
     
     
       23. The binder resin blend for toners according to claim 21 wherein the glass transition temperature is 54° to 66° C. 
     
     
       24. The binder resin blend for toners according to claim 21 wherein the softening temperature is 120° to 140° C. 
     
     
       25. The binder resin blend for toners according to claim 21 wherein the molecular weight (M W   H ) of the greatest peak in a high molecular weight region and the molecular weight (M W   L ) of the greatest peak in a low molecular weight region are in the relationship represented by the following equation (1):   1×10.sup.6 ≧M.sub.W.sup.H -M.sub.W.sup.L 2×10.sup.5( 1)     
     
     
       26. The binder resin blend of claim 1, wherein said acrylic monomer is 2-ethylhexyl acrylate present is in the copolymer in an amount of 5 to 30% by weight or diethylaminoethyl methacrylate present in the copolymer in an amount of 0.1 to 5% by weight.